In addition to the OS options people have already suggested, I will add that if you are stuck on android, you can at least install f-droid as an alternative to the google play store. It has a nice selection of foss apps that can at least help you in part of the journey out of the google ecosystem. I personally love the NewPipe app as an alternative front end for watching stuff on YouTube.
I will add a warning that installing a different OS on your phone in some cases can cause problems between the phone and the cell service provider. So research thoroughly for your specific case before doing that.
In addition to the OS options people have already suggested, I will add that if you are stuck on android, you can at least install f-droid as an alternative to the google play store. It has a nice selection of foss apps that can at least help you in part of the journey out of the google ecosystem. I personally love the NewPipe app as an alternative front end for watching stuff on YouTube.
I will add a warning that installing a different OS on your phone in some cases can cause problems between the phone and the cell service provider. So research thoroughly for your specific case before doing that.